add example: using aiohttp as client

examples/using_aiohttp_client.py

@@ -0,0 +1,61 @@
+import asyncio
+
+import aiohttp
+import audible
+
+
+class ClientRequest(aiohttp.ClientRequest):
+    def __init__(self, *args, **kwargs) -> None:
+        super().__init__(*args, **kwargs)
+        self.apply_auth_flow()
+
+    def apply_auth_flow(self) -> None:
+        body = self.body
+        if isinstance(body, aiohttp.BytesPayload):
+            body = body._value
+
+        sign_headers = audible.auth.sign_request(
+            method=self.method,
+            path=self.url.path_qs,
+            body=body,
+            adp_token=self._session._audible_auth.adp_token,
+            private_key=self._session._audible_auth.device_private_key
+        )
+        for header, value in sign_headers.items():
+            self.headers.add(header, value)
+
+
+class ClientSession(aiohttp.ClientSession):
+    def __init__(self, *args, audible_auth: audible.Authenticator, **kwargs):
+        if "request_class" in kwargs:
+            raise Exception("`request_class` keyword is not supported")
+
+        super().__init__(*args, request_class=ClientRequest, **kwargs)
+        self._audible_auth = audible_auth
+
+
+if __name__ == "__main__":
+    async def main(asin):
+        body = {
+            "supported_drm_types": ["Mpeg", "Adrm"],
+            "quality": "Extreme",
+            "consumption_type": "Download",
+            "response_groups": (
+                "last_position_heard, pdf_url, content_reference, chapter_info"
+            )
+        }
+
+        fn = "credentials.json"
+        auth = audible.Authenticator.from_file(fn)
+
+        async with ClientSession(audible_auth=auth) as session:
+            async with session.post(
+                f"https://api.audible.de/1.0/content/{asin}/licenserequest",
+                json=body
+            ) as r:
+                print(await r.json())
+                #print(r.request_info)
+                print(r.status)
+
+    loop = asyncio.get_event_loop()
+    loop.run_until_complete(main("B004V0WRPG"))